1. Field of the Invention
The present invention relates to networking technology. More particularly, the present invention relates to providing load sharing and redundancy in a network through a master router and a slave router having a shared set of interfaces in a single device.
2. Description of the Related Art
Networks are commonly used by organizations for a variety of purposes. For instance, through the use of networks, resources such as programs and data may be shared by users of the network. In addition, a computer network can serve as a powerful communication medium among widely separated users.
Communication among hosts and users of a network is often facilitated through connection to one or more routers. As shown in FIG. 1, a host 112 normally resides on a network segment 114 that enables its network entities to communicate with other entities or networks. Note that the host 112 need not directly connect to the entities or networks with which it communicates. For example, as shown in FIG. 1, the host 112 may be connected through a router R1 116. The router R1 116 may, in turn, connect one or more other routers such as router R2 118 with selected entities or networks.
Now, suppose that the host 112 wishes to send a message to a corresponding node 120. A message from the host 112 is then packetized and forwarded through the appropriate routers and to the corresponding node 120, as indicated by dotted line “packet from host” 122, according to a standard protocol. If the corresponding node 120 wishes to send a message to the host 112—whether in reply to a message from the host 112 or for any other reason—it addresses that message to the IP address of the host 112 on the network segment 114. The packets of that message are then forwarded to router R1 116 and ultimately to the host 112 as indicated by dotted line “packet to host” 124.
As described above, packets sent to and from the host 112 are forwarded via the router R1 116. As shown, the router R1 116 is the only route to and from the host 112. Thus, if the router R1 116 fails, communication with the host 112 becomes impossible. Accordingly, the reliability of the network as well as the routers in the network is of utmost importance.
As networks become a critical resource in many organizations, it is important that the networks are reliable. One way of achieving reliability is through redundancy. As described above, a single router failure may prevent communication to and from each host and user connected to the router. In many networks, it is common to provide redundancy through the use of multiple routers such that a backup router functions in the event of failure of a primary router. However, when the primary router fails, there is typically a “switchover time” that is required for the backup router to take over the functions of the primary router. As a result, such attempts to provide redundancy in switches suffer from a large switchover time. Accordingly, it would be beneficial if such redundancy could be provided with a reduction in the switchover time from a non-functional to a functional router.
In addition to reliability, it is often desirable to improve performance within a given network. In order to achieve this improvement, load sharing is often preferable. For instance, various users of a network may have a higher traffic level than other users of the network. It would therefore be desirable if performance could be achieved through the distribution of traffic among multiple routers.
In view of the above, it would be desirable if a redundancy and load sharing scheme could be implemented to reduce the switchover time upon failure of a router while implementing a load sharing scheme among multiple routers operating in a single device.